Incineration of certain types of refuse, including domestic refuse, yields an effluent stream of hot waste gases contaminated with mercury. Said stream also contains a certain amount of suspended particles known as fly ash, the composition of which varies, dependent on which type of refuse is being incinerated.
In said gas stream the mercury is present both as a component of the fly ash and as mercury vapor. By usual particle removing cleaning of the gas stream in a collector unit such as an electrostatic precipitator or a bag filter, only that part of the mercury is removed which is a component of the fly ash, whereas the mercury vapor will be emitted to the atmosphere together with the gas stream.
The problems of emitting to the atmosphere such mercury vapor-containing waste gases have long been recognized. However, these problems have not been solved, probably because the mercury vapor in question is diluted in very large amounts of waste gases, which in connection with the high volatility of mercury and mercury compounds make it difficult to prevent said mercury from being emitted to the atmosphere.